7 replies to this topic

[Procyon]

Need some help with this...perhaps some of you have found a way to make this work.

 

I have zero experience with refractors. Maybe, a little bit. A few nights ago I took out a 100mm Orion Astroview Deluxe f/6 600mm focal length refractor. I replaced the nosepiece of a 2" Baader Clicklock Diagonal with a TSFLAT and a 2" to T2 adapter. It made the view through a 31.5mm Antares 90 degree eyepiece feel Nagler like. Fantastic widefield view at 20x and 4.7º AFOV. 

 

I had brought a small case of 2 Pentax XW's (7 & 10mm) and an 8mm TV Delos to try instead of the 2 lbs hyperwides.  I could not reach focus with any of the 1.25" eyepieces inserted into an Antares 2" to 1.25" adapter.

 

Can someone explain to me why that is and how to work around it?    If I were to use an eyepiece such as the Morpheus with it's 2" sleeve, would that have worked? Or should I get some light weight 2" eyepieces instead?

 

Could be an excuse to get the T4's I love again....but yeah, that's a lot of money. 

 

I found this post, but not what to make of it. 

 

https://www.cloudyni...ner-for-visual/

 

 

Last Fall I did a test with all my 2" eyepieces, and some 1.25" eyepieces as well, in order to figure out exactly where their focal planes were relative to the flange on the barrel that rests against the diagonal.  When I do these eyepiece comparisons I start with a simple 1.25" eyepiece, a 12mm Plossl, whose focal plane is even with the flange on the barrel.  I then focus on a distant target over a mile away.  When, after switching eyepieces, I have to rack the focuser farther outward to regain focus on the same distant target, that means the focal plane of that eyepiece is down lower than the flange.  The Tele Vue Nagler Type 6 eyepieces are a prime example, where I usually need to rack the focuser outward another 8-9 mm compared to a lot of other 1.25" eyepieces.  Long focal length 1.25" eyepieces like 25mm and 32mm Plossls need the focuser to be racked farther inward, which means their focal planes are up above the flange.

 

When checking 2" eyepieces, I still start with the 1.25" 12mm Plossl in the 2" diagional, but I account for the thickness of the particular 1.25" adaptor I'm using in the 2" diagonal.  When I was testing an Orion 38mm Q70 (same as the Agena 38mm SWA) I moved the focuser perhaps only a millimeter or so after removing the 10mm-thick 1.25" adaptor.  That told me the focal plane of that 2" eyepiece was pretty far up inside, about 11 mm or so above the level of the flange on the barrel that was in contact with the top of the diagonal's 2" eyepiece holder.

 

 

[SeattleScott]

First of all, you aren’t specifying which way you are running out of focus, but I will assume you can’t focus far enough in.

If you are using a 2” diagonal, a Morpheus/Hyperion/LVW should work. Of course you need a watch your clearance when you insert the eyepiece in the diagonal, but it should be fine, as long as you aren’t threading a filter or barlow onto the 1.25” barrel before inserting it.

If you aren’t using a diagonal, going more pirate style, then you would need to look at clearance. I would assume the 1.25” barrel would smash the flattener if the eyepiece was inserted into the 2”-T2 adapter.

[Procyon]

If you are using a 2” diagonal, a Morpheus/Hyperion/LVW should work. Of course you need a watch your clearance when you insert the eyepiece in the diagonal, but it should be fine, as long as you aren’t threading a filter or barlow onto the 1.25” barrel before inserting it.
 

That's great news, thanks. 

 

Any way of making the Pentax and Delos 1.25" eyepieces reach focus while using the TSFLAT2 though? 

 

I wonder if this would work?

 

Astrosystems ultra-Low adapter - 2" to 1.25"

 

https://www.astrosys...ieceadapter.htm

 

Starman1, on 17 Nov 2024 - 5:02 PM, said:

Tele Vue 31mm Nagler, 21mm Ethos, 17mm Ethos focus about 10-10.2mm farther in than the focal plane of the scope.

If you use a 10mm tall 1.25" adapter, the 17.5mm Morpheus focuses 12.5mm farther in than the focal plane of the scope.

The Tele Vue Delos 14mm and 17.3mm focus 12.7mm farther in than the other focal lengths of Delos, so 5.8mm + the height of the adapter farther in than the focal plane of the telescope--potentially 15.8mm in.

Pentax XW 1.25" eyepieces focus in from the focal plane of the scope by the height of the adapter used.  2" XWs focus at the focal plane of the telescope.

 

3/4" out is an excellent recommendation.  It should allow the use of a Paracorr and/or many Barlows that focus inward.

 

So, it might be useful to have some figures at your fingertips for the height of various adapters.

You can tune the position of your eyepieces in the scope based on the height of the adapter.

A zero height adapter (rare) puts the eyepiee right at the focal plane of the scope if the eyepiece's focal plane is at the shoulder (most aren't).

 

(positive means above the telescope focal plane level, negative means below the level)

 

TeleVue Hi-Hat and brass adapters  +16.5mm

Tele Vue Paracorr 2 adapter  +10.5mm

Many twist-Lock types  +10mm-10.5mm

TeleVue flat top adapter +9.5mm

Baader Click-Lock adapter  +9.5mm

Astrosystems flat top adapter  +6mm

Tele Vue In-Travel adapter if the eyepiece rests on the outside of the adapter  +4mm

Baader Push-Fix adapter  +1.0mm

Glatter Parallizer adapter +0.0mm if the eyepiece fits in exactly to that point.

Starlight Instruments flat adapter  +0.0mm

Tele Vue In-Travel adapter if the eyepiece rests inside the outer lip  -1.5mm

Astrosystems ultra-Low adapter  up to -12.7mm depending on how far down inside the adapter the eyepiece fits.

 

https://www.cloudyni...-my-pentax-xws/

Edited by Procyon, 13 April 2025 - 09:58 AM.

[Procyon]

I give up lol. Just tried focusing on the clouds with 1.25" eyepieces without the TSFLAT2 and they won't, no matter which of the 3 adapters I have. If anyone knows how I can use 1.25" eyepieces in a 2" diagonal with this telescope let me know, 

 

PS> When I add the TSFLAT2 the 40mm Swan needed more in focus but would still not come into focus. A 5 and 9mm WO XWA came into focus with and without the TSF.

 

 

Edited by Procyon, 13 April 2025 - 01:31 PM.

[SeattleScott]

There is such a thing as a negative profile adapter but the eyepiece can’t be more than 1.8” wide, which could be a problem with XWs.

Otherwise yeah, Morpheus, LVW, Hyperion style eyepieces should work. The Morpheus give you something like 21mm of in focus when using the 2” barrel.

[Procyon]

There is such a thing as a negative profile adapter but the eyepiece can’t be more than 1.8” wide, which could be a problem with XWs.

Otherwise yeah, Morpheus, LVW, Hyperion style eyepieces should work. The Morpheus give you something like 21mm of in focus when using the 2” barrel.

Thanks man, all these years I've been using a Dobsonian in the beginning and than an 11" SCT for the past 7 years, I never really had a reason to look into focal planes, extension tubes, etc besides lightpath measurements when using binoviewers.

 

I will try an extension tube of 35 or 50mm and abandon 1.25" ep's if that doesn't work. Yeah, most of my 1.25"s are 2.2" or thicker. 

 

I wonder what happens to the view of this refractor when you add about 150mm of backfocus. And than to add a TSFLAT2 to complicate things even more, all just to use 1.25" ep's. Yeah, maybe I'm being too greedy.. Besides, I bought this refractor just for Asterisms and rich views, so why am I messing around with my 1.25mm ep's, makes no sense. 

 

The mount (Skywatcher Discovery) can clearly handle the scope and all my hyperwides. Was just getting annoyed when I'd remove a big eyepiece from the diagonal the refractor would like bounce but it always seems to go back to it's position. Was worried about mucking up the alignment.

 

Scope is acclimating outside, finally a nice night to do some observations. Thanks Scott.

Edited by Procyon, 13 April 2025 - 08:27 PM.

[25585]

Need some help with this...perhaps some of you have found a way to make this work.

 

I have zero experience with refractors. Maybe, a little bit. A few nights ago I took out a 100mm Orion Astroview Deluxe f/6 600mm focal length refractor. I replaced the nosepiece of a 2" Baader Clicklock Diagonal with a TSFLAT and a 2" to T2 adapter. It made the view through a 31.5mm Antares 90 degree eyepiece feel Nagler like. Fantastic widefield view at 20x and 4.7º AFOV. 

 

I had brought a small case of 2 Pentax XW's (7 & 10mm) and an 8mm TV Delos to try instead of the 2 lbs hyperwides.  I could not reach focus with any of the 1.25" eyepieces inserted into an Antares 2" to 1.25" adapter.

 

Can someone explain to me why that is and how to work around it?    If I were to use an eyepiece such as the Morpheus with it's 2" sleeve, would that have worked? Or should I get some light weight 2" eyepieces instead?

 

Could be an excuse to get the T4's I love again....but yeah, that's a lot of money. 

 

I found this post, but not what to make of it. 

 

https://www.cloudyni...ner-for-visual/

Do you need to use the 2" to T2 adapter?

[Procyon]

Do you need to use the 2" to T2 adapter?

I use this one: Baader 2" SCT Male to M48 Female Zero-length Reducing Adapter (Zero Optical Length) # M48-2 2454834

 

https://agenaastro.c...-2-2454834.html

 

 

I was looking at some old files I had and found all this...this is from the TS Optics site:

The recommended distances from the M48x0.75 thread to the camera sensor
In principle this rule applies: the shorter the refractor´s focal length, the longer the working distance to the sensor has to be.
focal length < 450 mm: 128 mm
focal length 450-490 mm: 123 mm
focal length 500-550 mm: 118 mm
focal length 560-590 mm: 116 mm
focal length 600-690 mm: 113 mm
focal length 700-800 mm: 111 mm
focal length ab 800 mm: 108 mm

An underrun or an overrun of the distance of up to 5% has no visible effect on the sharpness in the field of sensors with formats up to APS-C. With larger sensors, the tolerance is reduced to 1-2%.

 

https://www.teleskop...onnection-10307

 

TS-Optics TSFLAT2 Field Flattener    
Orion Deluxe 4" 600mm/F6 Focal length 600-690 mm: 113 mm   
Up to +-5% has no visible effect  113mm = 107-119mm Sweet Spot 
Baader 2" ClickLock Diagonal w/o Nosepiece Barrel 112mm 
    
41mm Panoptic 68 Minus 7mm 105mm  
35mm Panoptic 68 Minus 4 108mm  
31mm T5 Nagler 82 10 122mm  
Explore Scientific 30mm 82 Minus 3 109mm  
26mm T5 Nagler 82 0 112mm  
Explore Scientific 25mm 100°  8 120mm  
22mm T4 Nagler 82 7 119mm  
21mm 100° Ethos 10 122mm  
Explore Scientific 20mm 100º 15 127mm  
17mm 100° Ethos 10 122mm  
13mm 100° Ethos Minus 7 105mm  
Explore Scientific 12mm 92 0? 112mm  
10mm 100° Ethos Minus 7 105mm  
8mm 100° Ethos Minus 18 94mm  
6mm 100° Ethos Minus 18 94mm

More ep's: https://www.cloudyni...t/#entry3973139

 

Last night my 25mm ES 100 (Just barely), 20mm TS Optics 100 and 17mm Nikon HW would not come into focus.

 

But my 31.5mm Antares 90, 12mm ES 92, 9mm WO 101 and 5mm WO 110 did come into focus.

 

The numbers made sense....Wish I knew how to find an eyepiece's focal plane measurement before buying one.

 

I bought a 48mm Brandon last night I wonder what it's focal plane is? Would you happen to know 22585 or Richard? 

 

I ordered some cheapo extension rings also, but what is the point? I'll just be adding to the lightpath and make things worse I figure. 

Edited by Procyon, 14 April 2025 - 04:10 PM.